Simple Explanation

A way to cancel out unwanted sound by playing a reversed version of it.

Concise Technical Definition

The process of reducing or eliminating unwanted noise by introducing a signal that is identical in amplitude but opposite in phase to the noise.

Layman-Friendly Analogy

Like fighting fire with fire—sending in an equal but opposite wave to cancel the bad one.

Industry Usage Summary

Used in headphones, room acoustics, and professional audio environments. Includes active noise cancellation (ANC) in headphones and active bass traps in room acoustics, particularly for taming low-frequency room modes.

Engineering Shortcut

Real-time phase-inverted signal playback to cancel ambient or modal noise.

Full Technical Explanation

Noise cancellation is a technique used to reduce or eliminate unwanted ambient noise by generating a sound wave that is equal in amplitude but opposite in phase to the noise. When the two waves meet, they interfere destructively, effectively cancelling each other out. This principle is widely implemented in Active Noise Cancelling (ANC) headphones, which use microphones to sample ambient sounds and real-time digital signal processing to output inverse signals. In room acoustics, noise cancellation is also used in the form of active bass traps, which utilize microphones and speaker drivers to cancel problematic low-frequency modal resonances. These systems are most effective at low frequencies, where traditional passive treatments are less efficient. Noise cancellation improves clarity, comfort, and intelligibility in both personal listening and architectural acoustics applications.